In the past, methods of projecting a document image by using a projector have been utilized. In addition, techniques for enabling a projected image to be interactively operated have recently been developed, for the purpose of supporting users' work. As one example of these techniques, an augmented reality (AR) technique has been disclosed. In this technique, for example, when a user points his or her finger at a predetermined word contained in a projected image, a comment linked to this word appears in the image.
The above technique relies on a fixed or movable camera as an interface to pinpoint the location of a user's finger. A method of pinpointing the location of a user's finger employs, for example, a technique through which skin color components (color feature amounts) are extracted from a captured image so that the contour of a hand region in the image is extracted, and the location of a user's hand in this region is identified. Exemplary documents that describe such a method are listed below:
C. Prema et al., “Survey on Skin Tone Detection using Color Spaces”, International Journal of Applied Information Systems 2(2), published by Foundation of Computer Science, New York, USA, pages 18-26, May 2012; Ahmed et al., “Skin Detection—a Short Tutorial”, Encyclopedia of Biometrics by Springer-Verlag, Heidelberg, Berlin, 2009; Kakumanu et al., “A survey of skin-color modeling and detection methods”, Pattern Recognition, Volume 40, Issue 3, Pages 1106-1122, March 2007; and Vladimir et al., “A Survey on Pixel-Based Skin Color Detection Techniques”, PROC. GRAPHICON 2003.